1. Field of Invention
This invention relates in general to a retention device that prevents a cannula from becoming dislodged from the operative site during surgery. More particularly, this invention relates to a disposable retaining base providing secure attachment to the patient and facilitating the installation, substitution and adjustment of cannulae and instruments used in laparoscopic surgery.
2. Description of Related Art
Laparoscopic surgery is a recently introduced method for performing various types of surgical operations. Unlike other types of surgical procedures, laparoscopic surgery does not require large incisions to expose the internal organs. Typical laparoscopic procedures begin with the creation of a pneumoperitoneum (inflated peritoneum) in order to safely insert instruments into the body cavity. A small hole is first cut through the body wall and a tubular sheath or cannula is inserted through the hole. The body cavity is then distended by filling the body cavity with gas under pressure. Other cannulae are subsequently inserted into the body cavity to form housings for the insertion of various surgical instruments. For example, a laparoscope may be inserted through a cannula so that the surgeon can study ("visualize") the internal organs. Also, other types of surgical instruments may be inserted through these cannulae so that the surgery can be performed while the organs are being visualized and manipulated during the surgery.
There is often a need to restrain the instruments within the cannula to minimize excess movement, and a separate need to prevent excessive movement of the cannula itself, while allowing specific types of movement. If the cannula shifts through the incision as the surgeon carries out the operation, the laparoscope or other instruments may shift to affect the procedure or distract the surgeon and interfere with the operation. In addition, if a cannula becomes dislodged during the surgery, the distention of the body cavity may be lost. Both the re-establishment of the pneumoperitoneum and the re-insertion of the cannula prolong the length of the surgical procedure.
In addition there is often a need to adjust the position of the cannula or to adjust the angle of the cannula with respect to the patient's body without causing any unwanted shifting of the cannula. Such motion allows the surgeon to view other parts of the organs or to manipulate instruments relative to the organs during the surgery. Sometimes the cannula is made of material which is not treated with a special spiral retention device or is treated with a non-sticking material such as teflon. In such cases, special configurations or materials are needed to address these types of cannulae.
It is therefore desirable for the surgeon to have the cannula remain in proper position within the patient without the need to manually hold it in place thereby minimizing delays in such surgical procedures. It is also desirable to permit the hands of the surgeon to be kept free so that the surgeon may direct attention to other cannulae or other surgical needs. Therefore, ease of adjusting the retention force with the fingers of a single hand and placement of the trocar within the cannula is also an objective. Since various manufacturers make different sized cannulae, it is also desirable for cannulae retaining devices to be adaptable to different diameter cannulae.
In addition, it is sometimes desirable during a laparoscopic procedure to change the angle at which the cannula enters the body cavity in order to view different portions of the internal organs or to maneuver the other surgical instruments. However, such angulation can place excessive stress on the adhesive and cause it to separate. Thus, it is desirable to facilitate flexible but secure support a cannula in such a manner so that the angle can be changed with respect to the patient's body without causing any unwanted shifting of the cannula or enlargement of the peritoneum while insuring that minimum stress is placed upon the mounting pad and adhesive.
Finally, it is desirable to provide some gas sealing to prevent, or at least minimize, the escape of the gas around the incision through which the cannula is inseted.